One of conventional chip carriers for optical functional devices is described as a flat package for a laser coupler in an article entitled "Thin type optical pickup in which an optical system including a semiconductor laser is mounted on an actuator", on pages 100 and 101 in a journal "Nikkei Electronics", No. 534, 1991.
The conventional chip carrier includes a carrier body of insulating material, an external electrode connected to the laser coupler by a bonding wire, a transparent cover provided on one side of the carrier body, and a heat-dissipating plate provided on the other side of the carrier body.
In the conventional chip carrier, the laser coupler is electrically connected through the bonding wire and the external electrode to an external device, and is optically coupled through the transparent cover to an external device.
According to the conventional chip carrier, however, there are disadvantages in that a signal to be supplied to or from the laser coupler is attenuated due to a stray capacitance of the bonding wire and noise is included in the signal because the bonding wire acts as an antenna. Further, the chip carrier is large in size, because the external electrode is required to be located having a sufficient distance from the laser coupler. Furthermore, it is difficult to adjust the distance between the laser coupler and the transparent cover, so that the optical characteristics such as a focal distance of the optical device is unstable. As a result, it is difficult to use the chip carrier in combination with other optical devices.